Faucet valves that incorporate sliding ceramic plates have many advantages over other types of faucet valves. The ceramic elements are durable and provide for a long life with virtually no leakage between the two highly polished valving surfaces of the ceramic valve elements. However, in order for the ceramic valves to work in the faucet environment, the valves must be slidable under compressive force. Commonly, this compressive force is obtained by having the lower stationary valve member seated on resilient elastomeric seals. The upper portion of the valve must have all its elements dimensioned precisely so that the movable valve element will be under compressive force. Manufacturing tolerances have to be within a certain range in order for the resilient elastomeric seal to function properly. If the total height of the internal valve members is too great the elastomeric seal becomes overly compressed and the ceramic valve members are pressed against each other with too great a force and are therefore hard to operate.
On the other hand, if the total height of the internal valve members is too little, the resilient elastomeric seal pushes the fixed valve element fully upward but it still does not adequately press the two ceramic valve members together so that leakage between the fixed ceramic plate and the movable top ceramic plate still occurs.
Hydraulic pressure can also be used to press the stationary valve plate up against the ceramic valve disk. Hydraulic pressure is used to press ceramic disks together in a valve disclosed in my U.S. Pat. No. 4,250,912, issued on Feb. 17, 1981, entitled "A Faucet Valve".
What is needed is a mixing valve which can accommodate standard mixing valve cartridges and still use hydraulic pressure to assist in pressing the valve plates together to assist against leakage.